I wrote a post when iTunes won't allow me to watch a Disney movie: here's the link.
Well I had a recent problem when all of sudden, out of nowhere, iTunes won't sync that movie to my iPod, but all my other videos were synching (is that even a word?).
Anyway, I contaced Apple email support just to see what their response is. I don't trust them and I'm right not to. Their support page said they will contact me within 24 hrs, but I didn't get contacted until after 48 hrs. The solutions they gave me were complicated and involved too many steps. UGH and UGH again for Apple.
I solved the problem myself. Here's how to do it:
1. Open iTunes.
2. Connect iPod to computer. It will most likely sync automatically, let it.
3. On the left column of iTunes, your iPod's icon & name will pop up. Click on it.
4. There's a reset button. Click on it to reset your iPod to the factory/original setting.***
5. After your iPod resets, sync your movie to your iPod. It should work. Make sure your movie is selected/checkmarked to sync. For example, my setting is that iTunes will only sync the movies/videos I select/checkmark. However, you can set iTunes to automatically sync all movies/videos.
***NOTE: When you reset your iPod, you will lose your own settings. This is a drawback if you have your own settings. But at least you can watch your movie again.